The dynamics of speciation in the gall-forming aphid Geoica spp. within and among Pistacia host tree species

Abstract

Trees of the genus Pistacia serve as obligate hosts for gall-forming aphids (Hemiptera, Aphididae, Fordini). Each aphid species induces a characteristic gall on a single Pistacia host species. The genus Geoica (Fordini) induce similar spherical closed galls on the lower side of the leaflets midvein, on different Pistacia species. Two species of Pistacia trees that harbor Geoica galls grow naturally in Israel: P. palaestina and P. atlantica. We analyzed the phylogeny and the genetic structure of the Geoica species complex in Israel, and assessed the genetic differentiation and the level of host plant specificity of the aphids between P. atlantica and P. palaestina. We found that the splitting of the genus between P. atlantica and P. palaestina is estimated to have occurred 24-25 Ma (the Oligocene/Miocene boundary). Five different haplotypes suggesting five different species have been further speciating among Geoica spp., galling on P. atlantica, and an additional three species, on P. palaestina. Accession Numbers (COI sequences)MW452548 - Pp-Q-7d-Gamla - Haplotype-VI MW452549 - Pp-Q-10b-Gamla - Haplotype-VII MW452550 - Pp-A-1a-Mezar - Haplotype-VII MW452551 - Pp-S-6c-Sasa - Haplotype-VI MW452552 - Pp-New Hermon-2-5 - Haplotype-VIII MW452553 - Pa-Q-10a-II Gamla - Haplotype-IV MW452554 - Pa-Q-5d Gamla - Haplotype-II MW452555 - Pa-A-2f Mezar - Haplotype-IV MW452556 - Pa-E-13 Anafa - Haplotype-III MW452557 - Pa-K-10a Adolam - Haplotype-IV MW452558 - Pa-K-3a Adolam - Haplotype-II MW452559 - Pa-N-2a Nizana - Haplotype-I MW452560 - Pa-Z-1-3 Hazeva - Haplotype-I MW452561 - Pa-SL-3-3 Jordan-Sela - Haplotype-V